Method for monitoring existing telephone connections, particularly permanently switched telephone connections

Abstract

In a method for monitoring existing telephone connections, particularly permanently switched telephone connections, the information that correspond to one another and come from the redundant switching network halves (SN0, SN1 ) are compared to one another. The information intended for forwarding to connected lines is branched in the interface (LTU) at the line side into a separate time channel (K0) and is transmitted back to the interface (LIU) at the switching network side and are compared thereat to said information. Information coming from the lines is branched into the separate time channel and is transmitted in parallel with the original information to the interface (LIU) at the switching network side. The branched information is compared to the original information in the interface (LIV) at the switching network side. The procedures ensue time-channel-by-time-channel.

What is claimed is: 
     
       1. A method for monitoring existing telephone connections in a digital time-division multiplex telephone switching center having a redundant central switching network having first and second switching network halves, and the switching center having component parts of a peripheral line circuit area, comprising the steps of: a) comparing first information of a first time channel coming from said first switching network half to second information of a second time channel coming from said second switching network half, and continuing to step b) for a positive comparison of said first information and said second information;   b) branching one information of said first and second information, that is coming from said first and second switching network halves, respectively, and that is intended for forwarding, in a line side interface of the peripheral area pertaining to a connected subscriber line or trunk line, mirroring said one information onto a separate time channel, transmitting said mirrored information back to a network side interface at the central switching network of the peripheral area and comparing in said network side interface said received mirrored information to said one information coming from the switching network;   c) branching received information coming from the connected subscriber line or trunk line in the line side interface from an original time channel in which the received information appears, conducting said branched received information on a same connecting path as the original time channel in said separate time channel to said network side interface at the central switching network and comparing in said network side interface said branched received information to said received information of the original time channel; and   d) supplying, before repeating steps a), b) and c) for a further time channel, a check word in the network side interface at the central switching network and transmitting said check work in said separate time channel to the appertaining line side interface, mirroring said check word in said line side interface, transmitting said mirrored check word back to said network side interface at the central switching network, and comparing in the network side interface a pattern of said mirrored check word to a pattern of the supplied check word.   
     
     
       2. The method according to claim 1, wherein the separate time channel is a time channel serving for transmission of signaling information during switching service. 
     
     
       3. A method for monitoring existing telephone connections in a digital time-division multiplex telephone switching center having a redundant central switching network having first and second switching network halves, and the switching center at least having a network side interface operatively connected to a line side interface by a connection path, said connection path having time channels, said line side interface connected to a subscriber line or trunk line, comprising the steps of: a) comparing first information of a first time channel coming from said first switching network half to second information of a second time channel coming from said second switching network half, and continuing to step b) for a positive comparison of said first information and said second information;   b) for one information of said first and second information that comes from the central switching network to the network side interface and that is conveyed in a predetermined time channel of the connection path to the line side interface, branching said one information in the line side interface, mirroring said one information onto a separate time channel of the connection path, transmitting said branched and mirrored information back to the network side interface in the separate time channel of the connection path, and comparing the mirrored information to the one information in the network side interface;   c) for received information coming from the subscriber line or trunk line, branching the received information in the line side interface, mirroring said received information onto the separate time channel of the connection path, transmitting said received information to the network side interface in the predetermined time channel of the connection path and transmitting the mirrored received information to the network side interface in the separate time channel of the connection path, and comparing the mirrored received information to the received information in the network side interface;   d) supplying, before repeating steps a), b) and c) for a further time channel, a check word in the network side interface and transmitting said check work in said separate time channel to the line side interface, mirroring said check word in said line side interface, transmitting said mirrored check word back to said network side interface, and comparing in the network side interface a pattern of said mirrored check word to a pattern of the supplied check word.   
     
     
       4. The method according to claim 3, wherein the separate time channel is a time channel serving for transmission of signaling information during switching service. 
     
     
       5. A method for monitoring existing telephone connections in a digital time-division multiplex telephone switching center having a redundant central switching network, and the switching center at least having a network side interface operatively connected to a line side interface by a connection path, said connection path having time channels, said line side interface connected to a subscriber line or trunk line, comprising the steps of: a) for network information that comes from the central switching network to the network side interface and that is conveyed in a predetermined time channel of the connection path to the line side interface, branching said network information in the line side interface, mirroring said network information onto a separate time channel of the connection path, transmitting said branched and mirrored information back to the network side interface in the separate time channel of the connection path, and comparing said mirrored information to said network information in the network side interface;   b) for received information coming from the subscriber line or trunk line, branching said received information in the line side interface, mirroring said received information onto the separate time channel of the connection path, transmitting said received information to the network side interface in the predetermined time channel of the connection path and transmitting the mirrored received information to the network side interface in the separate time channel of the connection path, and comparing the mirrored received information to the received information in the network side interface;   c) supplying, before repeating steps a) and b) for a further time channel, a check word in the network side interface and transmitting said check work in said separate time channel to the line side interface, mirroring said check word in said line side interface, transmitting said mirrored check word back to said network side interface, and comparing in the network side interface a pattern of said mirrored check word to a pattern of the supplied check word.   
     
     
       6. The method according to claim 5, wherein the separate time channel is a time channel serving for transmission of signaling information during switching service.